[Easy Korean] Unit 17 -아/어야 해요 : must, have to, should

‘-아/어야 해요’ expresses necessity. ‘-아/어야 해요’ is used with adjectives, verbs and ‘-이다/아니다’, ‘있다/없다’. If the last vowel of the stem is ‘아’ or ‘오’, ‘-아야 해요’ is added. If the last vowel of the stem is a vowel other than ‘아’ or ‘오’, ‘-어야 해요’ is added. If the same ends with ‘-하다’, then ‘-하다’ becomes ‘-해야 해요’.